Crypt::RC4 is a simple implementation of the RC4 algorithm, developed by 
RSA Security, Inc. Here is the description from RSA's website: 

RC4 is a stream cipher designed by Rivest for RSA Data Security (now RSA 
Security). It is a variable key-size stream cipher with byte-oriented
operations. The algorithm is based on the use of a random permutation. 
Analysis shows that the period of the cipher is overwhelmingly likely to be
greater than 10100. Eight to sixteen machine operations are required per 
output byte, and the cipher can be expected to run very quickly in software.
Independent analysts have scrutinized the algorithm and it is considered 
secure.
